Experimental and simulation studies on gold bubble movement in gas-filled hohlraums

Abstract

A recent experiment on the Shenguang III laser facility has applied open-end gold hohlraums with two gas pressures to study the movement of a plasma bubble. Under a laser intensity and width close to those of an ignition main pulse, the bubbles possess radial scales from several hundred to one thousand micrometers. An x-ray framing camera is used to measure the N-band x-ray images generated from the gold bubble plasma at different moments, from which the edge positions of the expanding bubbles are accurately acquired. The experimental results are simulated by an optimized two-dimensional radiation hydrodynamic code. Based on the classical average atom (AA) model, two phenomenological coefficients Cer and Cop are introduced into the code to correct the bubble evolution. Cer artificially redistributes the energies between radiation and matter, and Cop correlatively adjusts the plasma opacity. The bubble movement simulated by the novel phenomenological model agrees better with the measured result than that by the AA model. This work plays a critical role in our code improvements and advances the reliability of the hohlraum design.

Investigation for the movement of the laser entrance hole and bubble plasmas in laser-driven hohlraum

“…So, it is of practical importance to study the movement of the LEH and bubble plasmas. In our previous research [19], we have observed the bubble movement in a simple open-end hohlraum. However, all of the previous works measure the boundary of the LEH and bubble plasmas with Static X-ray Imager or Gated X-ray Imager.…”

An improved view-factor method including plasma filling for angular distribution of radiation temperature from a laser-driven hohlraum

“…According to the conditions in the Au bubble experiment conducted on the hundreds of kJ laser facility [43][44][45], we get g b,g ≈90.…”

“…The experiments were conducted on the hundreds of kJ laser facility in China [43][44][45][47][48][49][50]. As shown in the figure 1, all the 32 laser beams of the outer cone with a total energy of 80.9 kJ and 3 ns flat-topped pulse, entered a hollow gold hohlraum (2.8 mm diameter and 2.08 mm length), which was filled with C 5 H 12 of 1.28 mg cc −1 .…”

Influence of laser-induced Au-plasma plume collision on the efficiency of x-ray radiations and the energy-transport process relevant to ICF

“…Plasma collision is a Universe phenomenon widely existing in High Energy Density Physics (HEDP) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17], laboratorybased astrophysics [2,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36], and Inertial Confinement Fusion (ICF) projects [37]. Since rich dynamic physics exist during the colliding process, a series of different configurations have been proposed by multi-beam laser-plasma interactions.…”

“…However, it is quite different in ICF physics that strong colliding processes occur more frequently. Especially, for the indirect-drive configuration where multi-laser beams are used to injected into a high-Z material hohlraum (gold or uranium) to provide an x-ray radiation source [37,39], plasma plumes from different focal spots of lasers will expand and collide with each other. There has been some previous work showing that bright x-ray radiations were produced during the plume colliding [37] It reveals that the local plasma evolution is complex and inhomogeneous in space.…”